Combination bulldozer blade and bucket

ABSTRACT

A combination bulldozer blade and bucket unit including means defining bucket means having a bulldozer blade supported thereon for movement from a first bucket forming position to a second bulldozer operation position. The bulldozer blade is operable as an ejector for removing material contained in the bucket means in response to movement of the blade from the first bucket forming position to the second bulldozer operating position. The bulldozer blade is supported on the unit whereby the blade bottom edge will be moved to a position in front of and below the leading edge of the bucket means and includes control means for effecting an automatic latching engagement between the blade and the leading edge of the bucket means in response to movement of the blade to the bulldozer operating position whereby the maximum forces developed against the blade in a bulldozing operation will be transmitted to the bucket means rather than to the blade linkage support means.

[ COMBINATlON-BULLDOZER BLADE AND BUCKET [75] Inventor: Donald RichardOlinger, Cedartown,

[73] Assignee: Rome Industries, Inc., Cedartown,

22 Filed: Nov. 23, 1971 21 App1.No.:.20l,354

[52] US. Cl 37/1175, 172/802, 214/147 [51] Int. Cl E021 3/76 [58] Fieldof Search 37/1 17.5; 172/802;

[56] References Cited UNITED STATES PATENTS 3,148,787 9/1964 Clark etal. 37/1 17.5 X

3,426,928 2/1969 Campbell 214/767 3,477,602 11/1969 Peterson 214/147 R X3,346,974 10/1967 Haynes 37/ll7.5 3,421,236 l/1969 Moyer 37/1l7.53,642,160 2/1972 Rockwell et al. 214/767 June 12, 1973 PrimaryExaminer-Robert E. Pulfrey Assistant Examiner-Eugene H. EickholtAtt0rneyNewton, Hopkins & Ormsby 57 ABSTRACT A combination bulldozerblade and bucket unit including means defining bucket means having abulldozer blade supported thereon for movement from a first bucketforming position to a second bulldozer operation position. The bulldozerblade is operable as an ejector for removing material contained in thebucket means in response to movement of the blade from the first bucketforming position to the second bulldozer operating position. Thebulldozer blade is supported on the unit whereby the blade bottom edgewill be moved to a position in front of and below the leading edge ofthe bucket means and includes control means for effecting an automaticlatching engagement between the blade and the leading edge of the bucketmeans in response to movement of the blade to the bulldozer operatingposition whereby the maximum forces developed against the blade in abulldozing operation will be transmitted to the bucket means rather thanto the blade linkage support means.

'15 Claims, 12 Drawing Figures COMBINATION BULLDOZER BLADE AND BUCKETBACKGROUND OF THE INVENTION This invention relates to the constructionindustry which requires movement of construction material, such as soilin excavation, wherein the soil is either moved by loading the soil ontotransport means or by pushing the soil along the ground from onelocation to another. More particularly, this invention relates to acombination bulldozer blade and bucket unit selectively operable as aloading bucket for transferring soil to transport means or operable as abulldozer blade for pushing or bulldozing soil along the supportingground.

A number of buckets and bulldozer blades have been provided for soilexcavation. However, the prior art bulldozer blades and buckets areindependent of each other and can only be used for the operation forwhich it is designed. Therefore, it was necessary to either provide twotranslating vehicles, one vehicle having a loading bucket and anothervehicle having a bulldozer blade, or provide a bulldozer blade and aloading bucket which are interchangeable with one translating vehicle,when it was desired to switch from a loading operation to a bulldozingoperation.

In certain types of bucket loading operations, it is often necessary toelevate the bucket to a maximum height, at which height it is difficultto maneuver the bucket for unloading the soil contained therein. Anumber of attempts have been made to provide an ejector blade for aloading bucket which is operable for ejecting soil from the bucketregardless of the elevated position. However, the buckets having anejector blade are not normally operable as a bulldozer blade. In usingan ejector blade of a bucket as a bulldozer blade, the bulldozingoperation would develop stresses and strains which would result indamage to the supporting linkage.

A number of attempts have been made to provide a combination bulldozerblade and bucket unit wherein the bulldozer blade would transfer theforces developed thereagainst directly to the bucket means. One suchcombination bulldozer blade and bucket means is disclosed in a U.S. Pat.to Haynes, No. 3,346,974 issued Oct. 17, 1967. The Haynes patentdiscloses a combination bulldozer blade and bucket wherein the bulldozerblade is operable as an ejector to remove soil from the bucket and wasalso operable in a bulldozing operation by movement of the blade to aposition in front of the bucket leading edge, for transferring theforces developed in a bulldozing operation directly to the bucket means.However, the blade support structure and control means of Haynes iscomplex in construction and uneconomical to manufacture. Further, thecombination bulldozer blade and bucket unit disclosed in the Haynespatent requires separate independent control means for moving thebulldozer blade to a position below the leading edge of the bucket forperforming a bulldozing operatiomThe combination bulldozer blade andbucket unit disclosed in the Haynes patent does not include means foreffecting a latching engagement between the bulldozer blade and thebottom edge of the bucket means for maintaining the blade in a fixedposition relative thereto in a bulldozing operation.

SUMMARY OF THE INVENTION The above disadvantages of the prior art havebeen overcome by the present invention which basically includes meansfor defining a bucket means having a pair of horizontally spacedsidewalls and a bottom wall having a leading edge. A bulldozer blademeans having a bottom edge is operatively associated with the bucketmeans for movement from a first bucket forming position with blade meansdisplaced rearwardly of the bucket leading edge to form a materialcontaining means, to a second bulldozer operating position with theblade bottom edge being located in front of and below the bucket leadingedge.

Control means is operatively associated with the bulldozer blade foreffecting movement of the blade between the two positions. An importantfeature of the present invention includes the blade support and controlmeans for effecting movement of the blade be tween the bucket formingposition and the bulldozer operating position, wherein the blade isautomatically moved to a position below the leading edge of the bucketmeans in response to movement of the blade to a position forward of theleading edge of the bucket means.

Another feature of the present invention includes means for effecting alatching engagement between the blade and a leading edge of the bucketmeans in response to movement of the blade to the bulldozer operatingposition.

The blade is supported relative to the bucket means whereby the bladebottom edge will move along an arcuate path adjacent to the bucketbottom portion for ejecting material contained therein in response tomovement of the blade from the bucket forming position to the bulldozeroperating position.

It is therefore a primary object of the present invention to provide acombination bulldozer blade and bucket unit selectively operable as aloading bucket or as a bulldozer blade.

A further object of this invention is to provide a combination bulldozerblade and bucket unit wherein the forces developed against the blade inthe bulldozer operating position will be transferred through the bucketbottom for reducing the amount of strain on the blade linkage supportmeans.

Another object of this invention is to provide a combination bulldozerblade and bucket unit including means for effecting a latchingengagement between the blade and the leading edge of the bucket inresponse to movement of the blade to the bulldozer operating posi--tion.

A still further object of this invention is to provide a linkage supportmeans for supporting a bulldozer blade on a bucket unit wherein theblade can serve as one wall of the bucket and can be moved relative tothe bucket means to eject material therefrom.

Still another object of this invention is to provide a support means forsupporting a bulldozer blade for movement relative to the bottom wall ofa bucket unit wherein the blade bottom edge moves along an arcuate pathadjacent the bucket bottom wall.

Yet another object of this invention is to provide a linkage supportmeans for supporting a bulldozer blade on a bucket unit whereby theblade can be selectively moved from a bucket forming position'to abulldozer operating position.

A further object of this invention is to provide a linkage support meansfor supporting a bulldozer blade on a bucket unit whereby the bulldozerblade can be bodily shifted in a translating movement between a bucketforming position and a bulldozer operating position.

Another object of this invention is to provide a linkage support meansfor supporting a bulldozer blade relative to a bucket unit whereby thebulldozer blade will be automatically moved to a position below and inlatching engagement with the leading edge of the bucket means inresponse to movement of the blade to a predetermined position forward ofthe leading edge of the bucket means.

An additional object of this invention is to provide a combinationbulldozer blade and bucket unit which is simple in construction andoperation, economical to BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is aperspective view of a combination bulldozer blade and bucket unitembodying the principles of the present invention;

FIG. 2 is an exploded perspective view as seen from the right rear ofthe bucket of FIG. 1 with certain parts broken away and shown in sectionand with certain parts being omitted for purpose of clarity;

FIG. 3 is a rear elevational view taken along line 33 of FIG. 4;

FIG. 4 is a vertical sectional view taken substantially along line 44 ofFIG. 3 showing the blade in a bucket forming position;

FIG. 5 is a vertical sectional view similar to FIG. 4 showing thebulldozer blade moved to an adjusted position;

FIG. 6 is a vertical sectional view similar to FIGS. 4 and 5 showing thebulldozer blade moved to a position of latching engagement with theleading edge of the bucket means;

FIG. 7 is a fragmentary vertical sectional view showing a modifiedsupport means for the bulldozer blade;

FIG. 8 is an exploded perspective view showing a modified connectionbetween a frame supporting arm and blade supporting arm;

FIG. 9 is an exploded perspective view showing a modified connection ofthe blade actuating assemblies;

FIG. 10 is a vertical sectional view of the combination bulldozer bladeand bucket utilizing the modified connections of FIGS. 8 and 9 andshowing the blade in a rearwardly retracted bucket forming position;

FIG. 11 is a vertical sectional view similar to FIG. 10 showing theblade in an intermediate adjusted position; and,

FIG. 12 is a vertical sectional view similar to FIGS. 10 and 11 showingthe bulldozer blade in a forward adjusted bulldozer operable position. 1

DESCRIPTION OF THE ILLUSTRATIVE EMBODIMENTS Referring now to thedrawings, the present invention will be described with reference to asupporting vehicle means 10, a bucket unit 30, and ejector and bulldozerblade and blade support and control means 100.

The function of the vehicle 10 is to provide a translating vehiclecapable of supporting and maneuvering the combination bucket unit andbulldozer blade in an excavation operation, such as loading soil onto atransport means or pushing soil in a bulldozing operation.

The function of the bucket unit 30 is to provide means shaped to definea forwardly opened cavity portion capable of containing material, suchas soil, to be loaded onto a transport vehicle.

The function of the blade 80 is to provide a combination blade capable'of either being used as an ejector and back wall of the bucket unit, orcapable of being used as a bulldozer blade for pushing soil in abulldozing operation.

The function of the blade support and control mechanism is to providemeans for supporting the blade 80 on the supporting framework inoperative association with the bucket unit 30 the blade can beselectively moved from the bucket forming and ejector position to thebulldozer operating position.

As shown in FIG. 1, the support vehicle 10 is a conventional bulldozerhaving track means 11 for providing a translating movement of thevehicle in the bucket loading and bulldozing operation. Vehicle 10 isprovided with a pair of forwardly projecting boom arm means 12, 13. Boomarms 12, 13 are pivotally supported on the tractor by convention] means(not shown) and are capable of being pivotally attached at their forwardends to the bucket unit 30. as will be described in more detailhereinbelow. The vehicle boom means 12, 13 are provided with ahydraulically controlled linkage mechanism for effecting pivotalmovement of the bucket 30 about a horizontal axis entending betweenpivots 53. The hydraulic control linkage mechanism includes a pair ofconventional hydraulic cylinder means 14, 15 which are operativelyconnected at their forward end to lever means 16, 17 respectively.Levers 16, 17 include link-members 18, 19 operatively connected to levermeans 20, (only one of which is shown in FIG. 1.) The lever means 20 arepivotally connected adjacent their lower depending ends (not shown) tothe boom means 12, 13 for pivotal movement about a horizontal axis. Theupper extended ends of the lever means 20 are pivotally connected to thebucket unit 30, about pivot support means 54, as will be described inmore detail hereinbelow, for effecting pivotal movement of the bucketunit 30 about a horizontal axis extending between pivots 53.

Referring now particularly to FIG. 2, the bucket unit 30 includes ahorizontally oriented arcuate shaped bottom wall means 31. Bottom wall31 is provided with a pair of sidewalls 32, 33. Sidewalls 32, 33 extendvertically upward in substantially parallel relationship from oppositeside edges of bottom wall 31. An upper extended end of sidewalls 32, 33are connected together by a horizontally extending frame means 34. Asshown in FIG. 4, the forward or leading edge of bottom wall 31 isprovided with a blade means 35 having a sharpened or beveled leadingedge 36. Sidewalls 32, 33 are provided with a vertically orientedreinforcing plate means 37, 38 extending along a forward edge thereof toprovide the required rigidity to the sidewall construction.

As shown in FIG. 2, the bucket bottom wall 31 includes a number ofopenings 39 operable for mounting a conventional shank member 40. Onlyone set of openings 39 and one shank member 40 have been illus trated inFIG. 2, however, it is to be understood that the bottom wall 31 could beprovided with a number of shank members 40 horizontally spaced acrossthe leading edge 35.

The bucket unit 30 is pivotally supported on the forwardly extending endof booms 12, 13 by a pair of horizontally spaced supporting frameworkmeans 41, 42. Each of the supporting framework means 41, 42 includes apair of horizontally spaced plate members 43, 44. Plate members 43, 44are vertically oriented in substantially parallel relationship and areconnected adjacent their lower end to the rear edge of bottom wall 31 byconventional means, such as welding. The upper ends of plate members 43,44 are connected to supporting arm means 45, 46. Arm means 45, 46 areconnected to the horizontally extending frame member 34 in substantiallyparallel relationship. Arm means 45, 46 include forwardly extending endportions 47, 48, respectively which project outwardly over the bucketbottom wall 31, as shown in FIGS. 4 and 5. The forwardly extended ends47, 48 are provided with sleeve means 49, 50 for providing a pivotalsupport for the blade means 80, as will be described in, more detailhereinbelow.

As shown in FIGS. 2-5, each of the plate members 43, 44 includes a lowerforwardly projecting portion 51 which extends underneath the bucketbottom wall 31. Connected to and extending horizontally outward fromeach of the forwardly projecting portions 51 is a skid plate member 52.The skid plate members 52 extend from adjacent a leading edge of the armmembers 51 rearwardly and upwardly around the lower portion of platemembers 43, 44, as shown in FIG. 2. Plate members 43, 44 are detailed inhorizontally spaced relationship for receiving the forwardly extendingends of the vehicle boom means 12, 13. The vehicle boom means 12, 13 arepivotally connected to the plate'members 43, 44 by a conventional pinmeans (not shown) which are inserted through pivot support means 53provided adjacent a lower edge thereof. The upward extended ends of thevehicle lever means are pivotally connected to the plate members 43, 44by pivot support means 54. Levers 20 are connected to the pivot supportmeans 54 by a conventional pin means (not shown). Downwardly extendingcurved plate members 55 are provided on the bucket unit 30 between thesidewalls 32, 33 and plate members 43, 44, as shown in FIGS. 2 and 3.The plate members 55 extend from adjacent a bottom'edge of frame element34, downwardly along a rear edge of sidewalls 32, 33 to a pointsubstantially midway between frame element 34 and bottom wall 31.

As shown in FIGS. 1 and 2, the blade means 80 is constructed of anarcuate shaped plate member having a reinforcing frame means 81extending around the rear edges thereof. Blade member 80 is providedwith a removable cutting edge 82. Cutting edge 82 is removably mountedon a bottom portion of blade 80 by a series of horizontally spacedconnecting bolt means 83.

As shown in FIG. 2, the rear surface of blade 80 is provided with a pairof vertically oriented and parallel arranged supporting frame means84,85. Each of the frame means 84, 85 includes a pair of horizontallyspaced, parallel arranged plate members 86, 87. Plate members 86, 87 aresecured to the rear surface of blade by conventional means, such aswelding (not shown). Plate members 86, 87 extend from adjacent the lowercutting edge of blade 80 upwardly to a point vertically spaced above theupper edge of blade 80. Connected to an upward extended end of theplates 86, 87 are a pair of horizontally arranged coaxially alignedsleeve elements 88, 89. Each of the frame support members 84, areprovided with a lower pivot support means 90 and an upper pivot supportmeans 91. Sleeves 88, 89 and pivot support means 90, 91 are detailed forproviding a pivotal connection for the blade supporting linkage, as willbe described in more detail hereinbelow.

The blade supporting frame means 84, 85 are detailed in horizontalspacing to be aligned with the bucket support arm means 45, 46, as willbe described in more detail hereinbelow.

As shown in FIGS. 4-6, blade 80 is provided with a rearwardly directedlatching surface portion 95. Latching surface portion 95 is detailed forlatching engagement with the forwardly extending leading edge 36, of thebucket bottom wall 31, substantially as shown in FIG. 6. The function ofthe latching surface 95 is to provide a latching engagement between thebucket bottom wall leading edge and blade 80 for maintaining the bladein a fixed position relative to the bucket bottom wall during abulldozing operation, whereby the forces developed against the blade 80will be transmitted to the bucket bottom wall structure.

Referring now particularly to FIGS. 2-6, the blade 80 is supported onthe supporting framework 41, 42, 45 and 46 in operative association withbucket unit 30 for movement from a first bucket forming position,substantially as shown in FIG. 4 wherein the blade 80 is displacedrearwardly from the leading edge of the bucket bottom wall and movableto a forwardly projected bulldozer operating position, substantially asshown in FIG. 6, wherein the bulldozer blade 80 is supported forward ofand beneath the leading edge 36 of bucket 30. In the forward bulldozeroperating position, the blade 80 is detailed in supported relationshipwhereby the latching surface 95 is in latching engagement with theleading edge 36 of the bucket bottom wall 31, substantially as shown inFIG. 6.

The bulldozer blade 80 is supported on the supporting framework 41, 42,45 and 46 in operative association with the bucket unit 30 by a pair oflinkage control assemblies 100. Linkage control assemblies areoperatively connected between supporting frame means 41, 42, 45 and 46and blade supporting frame means 84, 85. Since the linkage controlassemblies 100 are identical, both of the linkage assemblies will bedescribed concurrently. Linkage control assemblies 100 include a pairoflink members 101, 102. Link members 101, 102 are connected adjacentone end to the support arm members 49, 50 by conventional connectingpins 103 and retaining clips 104. Opposite ends of links 101, 102 areconnected to the blade sleeve members 88, 89 by pins 105 and retainingclips 106. In a connected relationship, as shown in FIG. 3, links 101,102 are supported on opposite horizontal edges of the sleeve elements49, 50, 88 and 89.

As shown in FIGS. 2-6, the linkage support assemblies 100 includes apair of link means 112, 113. Links 112, 113 are connected adjacent oneend to the upper pivot support means 91 provided on the blade supportingplate means 86, 87. Link means 112, 113 are connected to pivot supportmeans 91 by conventional connecting pins 114 which are maintained in anassembled relationship by conventional retaining clips 115. Oppositeends of the links 112, 113 are pivotally connected to actuating crankarm means 116 by connecting pins 117 which are maintained in assembledrelationship by conventional retaining clips 118.

Yieldable link means are pivotally connected between crank arm means 116and the blade lower pivot support means 90, as shown in FIGS. 4-6. Theyieldable link means includes a pair of link elements 120, 121. Linkelements 120 are pivotally connected to the pivot connecting pins 117adjacent one end and are pivotally connected adjacent their oppositeends to link elements 121 by connecting pins 122. The connecting pins122 are maintained in an assembled relationship by conventionalretaining clips 123. The opposite or forward ends of link elements 121are connected to the lower pivot means 90 by connecting pins 124. Sleeveelements 125 are provided around pins 122 between the connections oflink elements 121, 122. Limit stop means 126 are provided on links 120for abutting engagement with extending ear portions 127 formed on links121. Links 120, 121 are urged to a limit stop position by tension springmeans 128. Tension springs 128 are connected adjacent one end to theblade support plate means 86, 87 and are connected adjacent theiropposite ends to the sleeves 125 provided on the pivot pins 122. Withthe link members 120, 121 urged to a limit stop position, the earportions 127 of links 121 will be in abutting contact with the limitstops 126 formed on links 120.

Pivotal movement of the links 120, 121 in an opposite direction from thelimit stop position is effected by means of tab portions 130 formed onforwardly extending ends of crank arms 116. Tab portions 130 aredetailed for abutting engagement with bracket portions 131 of linkelements 120. The angular contact between tabs 130 and brackets 131 areadjustable by means of a set screw means 133 threadably supported in aconventional manner in crank arm tab portions 130. The pivotal operationof the links 120, 121 from a limit stop position to a yielded positionwill be described in more detail hereinbelow in the description of theoperation of the bucket control means.

As shown in FIGS. 2-6, the crank arms 116 are supported for pivotalmovement on the bucket frame supporting means 41, 42. Crank arms 116include a sleeve portion 140 detailed in lateral dimensions to fitbetween the plates 43, 44. Sleeves 140 are pivotally supported betweenplates 43, 44 by means of an elongated pin means 141. Crank arm sleeves140 include keyways 142 operative for receiving locking keys 143.Locking keys 143 are detailed for engagement within sleeve keyways 142and complementary keyways (not shown) on pins 141 whereby the crank arms116 are fixed to pins 141 for angular movement therewith. In anassembled relationship, pins 141 are inserted through pivot supportmeans 145 provided in plates 43, 44 and are held in an assembledposition therein by retaining clips 146. The locking key means 143 areoperative whereby angular displacement of pins 141 will effect acorresponding angular displacement of the crank arms 116.

Angular displacement of pins 141 is effected by means of hydrauliccontrol cylinder means 150. Cylinders 150 include conventionalreciprocally operable piston rod means 151. Extended ends of piston rodmeans 151 are connected between a pair of projecting arm means 152, 153by conventional pin means 154. Pins 154 are maintained in an assembledrelationship by retaining clips 155. Arms 152, 153 are fixed to extendedends of pins means 141 whereby movement of arms 152, 153 will effectpivotal movement of pins 141 and crank arms 116.

As shown in FIGS. 3-6, the upper ends of cylinders 150 are supported bypin means 155. Pin means 155 are supported adjacent one end by bracketmeans 156 extending rearwardly from bucket frame element 34. Oppositeends of pins 155 are supported by collar means 157 provided on thesidewalls of bucket arm frame means 45, 46. Collar means 157 arecoaxially aligned relative to openings extending through the bracketmeans 156. Pin means 155 are secured in a fixed position relative to thebrackets 156 and collars 157 by means of locking screw means 158. Thus,it can be seen that operation of hydraulic cylinder means 150 willeffect movement of piston rods 151, thereby rotating crank arm means116, as described hereinabove. The hydraulic cylinder means 150, 151 areprovided with conventional supply lines 159 connected to conventionalhydraulic pump means (not shown) for effecting operation of thecylinders.

In a bucket loading operation, blade is supported in a position,substantially as shown in FIG. 4, with the blade rearwardly displacedfrom the leading edge 36 of the bucket bottom and with the linkageassemblies displaced upwardly by operation of the hydraulic cylindermeans 150. Blade 80 is detailed in horizontal dimensions tosubstantially fill the space between bucket sidewalls 32, 33 and willfunction as the bucket backwall when in a retracted rearwardly displacedposition.

To utilize the blade 80 as an ejector for removing soil contained in thebucket 30, hydraulic cylinder means are operated to drive the pistonrods 151 to an extended position. Movement of piston rods 151 to anextended position will effect a pivotal movement of crank arm means 116thereby moving the blade forwardly within the bucket means to eject anymaterial contained therein. In utilizing the blade 80 as an ejector, theblade will be moved to a position forwardly displaced from the leadingedge 36 of the bucket bottom wall 31. Movement of the ejector blade 80in an ejecting operation is controlled by the linkage assemblies 100whereby the blade bottom cutting edge 82 will move along an arcuate pathadjacent the bucket bottom wall 31 to scrape and eject any materialcontained thereon. The linkage assemblies 100 will allow the blade 80 tobe bodily displaced in a translating motion from the rearwardlyretracted bucket forming position to the forward material ejectingposition. In movement of the blade 80 from the rearwardly retractedbucket forming position to the forward ejector position, blade 80 willbe allowed to bodily pivot, relative to the bucket bottom 31, about thepivotal connection of crank arm pin means 117, for maintaining bladecutting edge 82 adjacent bottom wall 31.

In utilizing blade 80 in a bulldozing operation, the blade is moved fromthe position shown in FIG. 5 to the position shown in FIG. 6, with theblade latching surface means 95 supported in latching engagement withthe forward leading edge 36 of bucket bottom wall 31. Movement of theblade 80 to a latching position is effected by continued operation ofthe hydraulic cylinder means 150 afte r'the blade has reached a positionlocated slightly ahead of the bucket buttom wall 31. During movement ofthe blade 80 from the retracted bucket forming position to the forwardlydisplaced ejector position, the yieldable link means 120, 121 aremaintained in a limit stop position as described hereinabove by thetension spring means 128.

A continued clockwise movement of crank arm means 116 after blade 80reaches a predetermined position forward of bucket leading edge 36,substantially as shown in FIG. 5, will effect a downward displacement ofthe blade 80 until a blade abutment portion 95a contacts the leadingedge 36 of bucket bottom wall 31. After abutment portion 95a contactsbucket leading edge 36, a continued clockwise movement of rotary crankarm means 116 will cause set screw means 133 to contact brackets 131thereby effecting an angular displacement of link means 120, 121 in adirection away from their limit stop position. Movement of link means120, 121 away from their limit stop position will effect a rearwardcamming displacement of abutment surface portion 95a to bring the latchmeans 95 into contact with the lower surface of bucket leading edge 36.

During movement of the blade 80 from the bucket forming position, to thebulldozer operating position, the blade will travel in a first directionalong an arcuate path and will automatically move in a second directionin response to the blade reaching a predetermined location forward ofthe bucket leading edge 36. Blade 80 is held in a bulldozer operatinglatched position by maintaining hydraulic control cylinder means 150 inan expanded condition.

The. bulldozer blade means 80 is disengaged from latching engagementwith the bucket leading edge by retracting the hydraulic cylinder means150, which will in turn effect a counterclockwise movement of crank arms116. A counterclockwise movement of crank arms 116 will disengage thecrank arm set screw means 133 from bracket means 131. A disengagement ofset screw means 133 from bracket 131 will allow the tension spring means128 to return link means 120, 121 to their limit stop position. A returnmovement of link means 120, 121 to their limit stop position willadvance blade 80 slightly forward to remove latching surface 95 fromengagement with the bucket leading edge 36. A continued counterclockwisemovement of crank arms 116 will retract the blade 80 to the bucketforming position, as shown in FIG. 4, with crank arms 116 and link means112, 113, 120, 121 disposed within a cavity defined between thesidewalls of bucket supporting frame means 45, 46.

Referring now to FIG. 7, a modification of the blade support means isprovided. The bucket 30 and blade means 80 shown in FIG. 7 are identicalto the bucket and blade provided in FIGS. 1-6 above, except that thelinkage means 112, 113, 120 and 121 have been omitted. In place of thelinkage 112, 113 120 and 121, fixed arm means are connected to the bladesupporting plate means 86, 87 and extend rearwardly therefrom. Extendedrear ends of arms 180 are connected to forwardly projecting ends ofcrank arms 116 by conventional pin connecting means 181. Pin means 181extend through elongated angularly displaced slots 182 provided in armmeans 180. Pin means 181 are supported in an upper limit pivotalposition during movement ofthe blade between the bucket formin'gposition to the ejector position and is allowed to displace downwardlyalong slot 182 during movement of the blade to the bulldozer operatingposition. Pin means 181 are urged to the upper limit pivot positionwithin slots 182 by tension spring means 183. Tension spring means 183are connected adjacent one end to pins 181 and are connected adjacenttheir opposite ends to fixed bracket means 184 extending rearwardly fromblade supporting plate means 86, 87.

As shown in FIG. 7, blade plate means 86, 87 are provided withrearwardly extending bracket support means 185. Journaled for rotationrearwardly extending ends of bracket means 185 are roller elements 186.Roller elements 186 operate as abutment stop means for blade means 80during downward displacement of the blade 80 to the bulldozer operableposition. In movement of the blade 80, shown in FIG. 7, from the bucketforming position to the bulldozer operating position, pivot pins 181will be maintained in the upper limit pivot position during movement ofthe blade from the rearwardly retracted bucket forming position to theforwardly displaced ejector position. After the blade 80 has reached apredetermined position forward of bucket bottom wall 31, a continuedmovement of crank arm means 116 will displace blade 80 downwardly untilroller means 186 contact the upper surface of bucket blade 35. Acontinued movement of crank arm means 116 after rollers 186 havecontacted blade 35, will cause pin means 181 to be displaced downwardlywithin elongated slots 182. A downward displacement of pin means 181relative to slots 182 will effect a camming displacement of blade 80rearwardly. A rearward displacement of blade 80 will cause rollers 186to roll over the surface of bucket blade 35 to bring the blade latchingsurface into contact and in latching engagement with the leading edge 36of the bucket blade element 35. Blade 80 is disengaged from the latchingpositionand returned to the bucket forming position by effectingoperation of cylinder means to rotate crank arm means 116 in acounterclockwise direction. A counterclockwise movement of crank armmeans 116 will displace pin means 181 upwardly within elongated slots182 thereby camming blade 80 forward to remove latching surface 95 fromengagement with the blade leading edge 36. After the pin means 181reaches the upper limit pivot position within slots 182, a continuedcounterclockwise movement of crank arm means 116 will effect a firstupward movement and then a rearwardly retracting movement of the blade80 to the bucket forming position described hereinabove.

MODIFIED CONNECTION OF THE BLADE SUPPORTING MECHANISM pair of links 101,102 and retaining pins 103, 105. In

the modified arrangement, links 101, 102 are connected to an adjustmentassembly including a pin 201 having a sleeve 202. Links 101, 102 areconnected to sleeve 202 by retianing pin 103. Also supported on pin 103is a pair of supporting links 204, 205. The opposite end of links 204,205 are supported on a retaining pin 206 inserted through sleeve 49.

As shown in FIG. 8, pin 201 includes an externally threaded portionwhich is inserted through an opening 207 formed on an upstanding bracket208 mounted on the upper surface of arms 45, 46. Pin 201 is slidable inopening 207 and is secured in a selectively set position by a pair oflocking nuts 209, 210.

The adjustable connecting assembly between support arm 45 and blade arm84 will permit the support pin 103 to be adjusted about the axis ofconnecting pin 206.

As shown in FIG. 9, the linkage support assembly connected between arm116 and blade arm 85 are identical to the linkage system describedhereinabove except that the pair of links 121 has been replaced by anadjustable link 215. Adjustable link 215 includes a first link portion216 which is pivotally attached to the lower pivot means 90 by aconventional pivot pin means 90a. Link portion 216 includes aninternally threaded opening 217 adapted to receive an externallythreaded second link portion 218. Threaded shank portion 218 includes ahead 219 having opening 220 adapted to receive pivot pin means 122.Projecting forwardly from head portion 219 is a limit stop flange 220.Limit stop flange 220 is adapted to cooperate with a limit stop lug (notshown) provided between linkage 120 for controlling the amount ofpivotal movement of links 120 relative to the adjustable link 215.

The above described adjustable linkage connecting means includingadjustable pin 201 and adjustable link 215 are provided so that thesupported bulldozer blade 80 can be adjusted to a detail set positionrelative to the bucket botton 31, whereby the lower edge of the bladewill have sufficient clearance when adjusted between the bucket formingposition and the bulldozer operable position. The adjustment mechanismwill also ensure that the lower edge of the blade can be maintained inclose proximity to the bucket bottom 31 to ensure that the materialcontained in the bucket will be sufficiently ejected during forwardadjustment of blade 80.

Referring now particularly to FIGS. -12, an adjustment of pin 201 toeffect clockwise movement of pin 103 will lower the blade relative tothe bucket bottom 31 and a counterclockwise movement of pin 103 byadjustable pin 201 will raise the blade relative to the bucket bottom.Further, an adjustment to lengthen link 215 will also lower the bladerelative to the bucket bottom 31 and an adjustment to shorten link 215will raise the blade relative to the bucket bottom.

The bucket, blade and linkage support and control mechanisms areconstructed of conventional metal stock material which will provide thedesired rigid supporting characteristics necessary to perform bucketloading and bulldozer operations mentioned hereinabove. The fixed orrigid connections between adjacent metal stock members of the bucket andblade means are formed in a conventional manner, such as welding (notshown).

it now becomes apparent that the above described illustrativeembodiments embodying the principles of the present invention arecapable of obtaining the above stated objects and advantages. It isobvious that those skilled in the art may make modifications in thedetails of construction without departing from the spirit oftheinvention which is to be limited only by the scope of the appendedclaims.

What is claimed is:

1. A combination bulldozer blade and bucket unit comprising, incombination:

a. means on said unit defining a portion of a bucket unit including apair of horizontally spaced sidewalls and a bottom wall having a leadingedge;

. a movable blade having a bottom edge;

. means supporting said blade on said unit for movement from a firstbucket forming position with said blade displaced rearwardly of saidleading edge above said bottom wall and between the rearward portions ofsaid side walls to provide the rear wall of said bucket unit to a secondbulldozer operating position with said blade bottom edge being locatedin front of and below said bottom wall leading edge; and,

d. means for effecting a latching engagement between the leading edge ofsaid bottom wall and a lower portion of said blade in response tomovement of said blade to said second bulldozer operating position.

2. A combination bulldozer blade and bucket unit as described in claim 1further characterized in that said blade includes a rearwardly directedshaped latching surface formed adjacent the bottom edge thereof andwherein said shaped latching surface is detailed for latching engagementwith said leading edge of said bottom wall in response to movement ofsaid blade to said second bulldozer operating position.

3. A combination bulldozer blade and bucket unit as described in claim 1further characterized in that control means is operatively associatedwith said unit for effecting movement of said blade between said twopositions.

4. A combination bulldozer blade and bucket unit as described in claim 1further characterized in that said unit includes control meansoperatively associated with said unit for effecting movement of saidblade between said two positions, said control means including firstlink means pivotally connected to an upper portion of said blade andfurther including second link means connected to an intermediate portionof said blade, said first and second link means being operativelyassociated with each other and with said blade whereby said blade canbodily pivot relative to said bottom wall during said movement from saidfirst position to said second position.

5. A combination bulldozer blade and bucket unit as described in claim 1further characterized in that control means is operatively associatedwith said unit for effecting movement of said blade between said twopositions, said control means and said blade supporting means beingoperatively associated with each other whereby said blade is bodilyshifted in a translating motion from said first position to said secondposition.

6. A combination bulldozer blade and bucket unit comprising, incombination:

a. means on said unit defining a portion of a bucket unit including apair of horizontally spaced sidewalls and a bottom wall having a leadingedge;

b. a movable blade having a bottom edge;

c. means supporting said blade on said unit for movement from a firstbucket forming position with said blade displaced rearwardly of saidleading edge above said bottom wall and between the rearward portions ofsaid side walls to provide the rear wall of said bucket unit to a secondbulldozer operating position with said blade bottom edge being locatedin front of and below said bottom wall leading edge; and,

d. control means operatively associated with said unit for effectingmovement of said blade between said two positions, said control meansand said blade supporting means being operatively associated with eachother whereby said blade is bodily shifted in a translating motion fromsaid first position to said second position.

7. A combination. bulldozer blade and bucket unit as described in claim6 further characterized in that said control means and said bladesupporting means include first linkage means pivotally connected to andoperable for supporting an upper portion of said blade, second linkagemeans connected to an intermediate portion of said blade, actuatingmeans operatively connected to said second linkage means for effectingmovement of said blade from said first position to said second position,and wherein said second linkage means is operatively connected to saidblade for effecting said bodily translating movement of said blade fromsaid first position to said second position in a first direction andwherein said second linkage means includes means for effecting movementof said blade in a second direction angularly disposed to said firstdirection in response to said blade reaching a predetermined locationrelative to the leading edge of said bottom wall.

8. A combination bulldozer blade and bucket unit comprising, incombination:

a. means on said unit defining a bucket means having a pair ofhorizontally spaced sidewalls and a bottom wallhaving a leading edge;

b. a bulldozer blade having a bottom edge;

0. means supporting said bulldozer blade on said unit for movement froma first bucket forming position displaced rearwardly of said leadingedge to a second bulldozer operating position with said blade bottomedge being located in front of and below said bottom wall leading edge;

d. control means operatively associated with said unit for effectingmovement of said bulldozer blade between said two positions, saidcontrol means including first linkage means pivotally connected to andoperable for supporting an upper portion of said blade, second linkagemeans connected to an intermediate portion of said blade, actuatingmeans operatively connected to said second linkage means for effectingmovement of said blade from said first position to said second position,and wherein said second linkage means is operatively connected to saidblade means for effecting a bodily translating movement of said bladefrom said first position to said second position, with said translatingmovement being in a first direction along a predetermined path andwherein said first and second linkage means and said actuating means areoperatively associated with each other and with said blade for effectingmovement of said blade in a second direction along a path angularlydisposed relative to said first direction in response to said bladereaching a predetermined location relative to the leading edge of saidbucket means, and

e. said second linkage means including arm means fixed to and extendingrearwardly from said bulldozer blade and said actuating means includinga power controlledcrank arm having an extended end pivotally connectedto said rearwardly extending arm means of said blade so that a pivotalmovement of said crank arm will effect said movement of said bulldozerblade between said two positions and along said two directions ofmovement,

said pivotal connection between said rearwardly extending arm means ofsaid blade and said power controlled crank arm including an elongatedslot and pivot pin means, said elongated slot being detailed in angularrelation relative to said bulldozer blades so that sliding movement ofsaid pivot pin means within said elongated slot means will effect acamming displacement of said bulldozer blade to a position of latchingengagement with a leading edge of-said bucket means.

9. A combination bulldozer blade and bucket unit as described in claim 8further characterized inthat said bulldozer blade includes abutment stopmeans detailed in location thereon for abutting contact with an uppersurface portion of said bucket in response to movement of said bulldozerblade to said second bulldozer operating positions and wherein saidcamming operation of said pivot pin means and said elongated slot meansis effective in response to abutting contact between said bulldozerblade abutment stop means and said bucket.

10. A combination bulldozer blade and bucket unit as described in claim9 further characterized in that said elongated slot and pivot pin meansincludes spring biasing means for maintaining said pivot pin means in afirst position with said elongated slot during a first portion ofmovement of said bulldozer blade from said first bucket forming positionto a predetermined location relative to the leading edge of said bucketmeans and wherein said spring biasing means is yieldable in response tosaid bulldozer blade reaching said predetermined location for allowing ayielding movement of said pivot pin means relative to said elongatedslot means to effect said camming displacement of said bucket means tosaid latched position.

11. A combination bulldozer blade and bucket unit comprising, incombination:

a. means on said unit defining a bucket means having a pair ofhorizontally spaced sidewalls and a bottom wall having a leading edge;'

b. a bulldozer blade having a bottom edge;

c. means supporting said bulldozer blade on said unit for movement froma first bucket forming position displaced rearwardly of said leadingedge to a second bulldozer operating position with said blade bottomedge being located in front of and below said bottom wall leading edge;

(1. control means operatively associated with said unit for effectingmovement of said bulldozer blade between said two positions, saidcontrol means ineluding first linkage means pivotally connected to andoperable for supporting an upper portion of said blade, second linkagemeans connected to an intermediate portion of said blade, actuatingmeans operatively connected to said second linkage means for effectingmovement of said blade from said first position to said second position,and wherein said second linkage means is operatively connected to saidblade means for effecting a bodily translating movement of said bladefrom said first position to said second position, with said translatingmovement being in a first direction along a predetermined path andwherein said first and second linkage means and said actuating means areoperatively associated with each other and with said blade for effectingmovement of said blade in a second direction along a path angularlydisposed relative to said first direction in response to said bladereaching a predetermined location relative to the leading edge of saidbucket means; and e. said actuating means including a pivotally movablecrank arm means and said second linkage means including link meanshaving one end pivotally connected to an extended end of said crank armmeans and with a second end pivotally connected to said bulldozer blademeans, and yieldable latching means operatively associated with saidlink means for maintaining said link means in angularly set positionrelative to said bulldozer blade during movement of said bulldozer bladefrom said first bucket forming position to a predetermined positionlocated in front of the leading edge of said bucket means, saidyieldable latch means being operable for permitting pivotal movement ofsaid link means relative to said blade means in response to saidbulldozer blade reaching said predetermined position. 12. A bulldozerblade and bucket unit as described in claim 11 further characterized inthat said yieldable latch means includes a pair of link elementspivotally connected to each other and with one of said link elementsbeing pivotally connected to said bulldozer blade means and said otherlink elements being pivotally connected to said second link means andwherein said link elements include limit stop means for controlling thepivotal movement of said link elements in a limit stop position in onedirection and permitting the pivotal movement of said link elements inan opposite direction and wherein spring biasing means is operativelyassociated with said link elements for biasing said link elements tosaid limit stop position.

13. A bulldozer blade and bucket unit as described in claim 12 furthercharacterized in that said actuating crank arm means includes means foreffecting movement of said link elements in said opposite direction awayfrom said limit stop position in response to said bulldozer bladereaching said predetermined location forward of said leading edge ofsaid bucket means.

14. Apparatus as in claim 8 wherein said means for effecting movement ofsaid bulldozer blade includes a hydraulic control cylinder means.

15. Apparatus as in claim 11 further including means for effecting alatching engagement between the leading edge of said bucket means and alower portion of said bulldozer blade means when said last-mentionedmeans is in bulldozer operating position.

1. A combination bulldozer blade and bucket unit comprising, incombination: a. means on said unit defining a portion of a bucket unitincluding a pair of horizontally spaced sidewalls and a bottom wallhaving a leading edge; b. a movable blade having a bottom edge; c. meanssupporting said blade on said unit for movement from a first bucketforming position with said blade displaced rearwardly of said leadingedge above said bottom wall and between the rearward portions of saidside walls to provide the rear wall of said bucket unit to a secondbulldozer operating position with said blade bottom edge being locatedin front of and below said bottom wall leading edge; and, d. means foreffecting a latching engagement between the leading edge of said bottomwall and a lower portion of said blade in response to movement of saidblade to said second bulldozer operating position.
 2. A combinationbulldozer blade and bucket unit as described in claim 1 furthercharacterized in that said blade includes a rearwardly directed shapedlatching surface formed adjacent the bottom edge thereof and whereinsaid shaped latching surface is detailed for latching engagement withsaid leading edge of said bottom wall in response to movement of saidblade to said second bulldozer operating position.
 3. A combinationbulldozer blade and bucket unit as described in claim 1 fuRthercharacterized in that control means is operatively associated with saidunit for effecting movement of said blade between said two positions. 4.A combination bulldozer blade and bucket unit as described in claim 1further characterized in that said unit includes control meansoperatively associated with said unit for effecting movement of saidblade between said two positions, said control means including firstlink means pivotally connected to an upper portion of said blade andfurther including second link means connected to an intermediate portionof said blade, said first and second link means being operativelyassociated with each other and with said blade whereby said blade canbodily pivot relative to said bottom wall during said movement from saidfirst position to said second position.
 5. A combination bulldozer bladeand bucket unit as described in claim 1 further characterized in thatcontrol means is operatively associated with said unit for effectingmovement of said blade between said two positions, said control meansand said blade supporting means being operatively associated with eachother whereby said blade is bodily shifted in a translating motion fromsaid first position to said second position.
 6. A combination bulldozerblade and bucket unit comprising, in combination: a. means on said unitdefining a portion of a bucket unit including a pair of horizontallyspaced sidewalls and a bottom wall having a leading edge; b. a movableblade having a bottom edge; c. means supporting said blade on said unitfor movement from a first bucket forming position with said bladedisplaced rearwardly of said leading edge above said bottom wall andbetween the rearward portions of said side walls to provide the rearwall of said bucket unit to a second bulldozer operating position withsaid blade bottom edge being located in front of and below said bottomwall leading edge; and, d. control means operatively associated withsaid unit for effecting movement of said blade between said twopositions, said control means and said blade supporting means beingoperatively associated with each other whereby said blade is bodilyshifted in a translating motion from said first position to said secondposition.
 7. A combination bulldozer blade and bucket unit as describedin claim 6 further characterized in that said control means and saidblade supporting means include first linkage means pivotally connectedto and operable for supporting an upper portion of said blade, secondlinkage means connected to an intermediate portion of said blade,actuating means operatively connected to said second linkage means foreffecting movement of said blade from said first position to said secondposition, and wherein said second linkage means is operatively connectedto said blade for effecting said bodily translating movement of saidblade from said first position to said second position in a firstdirection and wherein said second linkage means includes means foreffecting movement of said blade in a second direction angularlydisposed to said first direction in response to said blade reaching apredetermined location relative to the leading edge of said bottom wall.8. A combination bulldozer blade and bucket unit comprising, incombination: a. means on said unit defining a bucket means having a pairof horizontally spaced sidewalls and a bottom wall having a leadingedge; b. a bulldozer blade having a bottom edge; c. means supportingsaid bulldozer blade on said unit for movement from a first bucketforming position displaced rearwardly of said leading edge to a secondbulldozer operating position with said blade bottom edge being locatedin front of and below said bottom wall leading edge; d. control meansoperatively associated with said unit for effecting movement of saidbulldozer blade between said two positions, said control means includingfirst linkage means pivotally connected to and operable for supportingan upper porTion of said blade, second linkage means connected to anintermediate portion of said blade, actuating means operativelyconnected to said second linkage means for effecting movement of saidblade from said first position to said second position, and wherein saidsecond linkage means is operatively connected to said blade means foreffecting a bodily translating movement of said blade from said firstposition to said second position, with said translating movement beingin a first direction along a predetermined path and wherein said firstand second linkage means and said actuating means are operativelyassociated with each other and with said blade for effecting movement ofsaid blade in a second direction along a path angularly disposedrelative to said first direction in response to said blade reaching apredetermined location relative to the leading edge of said bucketmeans, and e. said second linkage means including arm means fixed to andextending rearwardly from said bulldozer blade and said actuating meansincluding a power controlled crank arm having an extended end pivotallyconnected to said rearwardly extending arm means of said blade so that apivotal movement of said crank arm will effect said movement of saidbulldozer blade between said two positions and along said two directionsof movement, f. said pivotal connection between said rearwardlyextending arm means of said blade and said power controlled crank armincluding an elongated slot and pivot pin means, said elongated slotbeing detailed in angular relation relative to said bulldozer blades sothat sliding movement of said pivot pin means within said elongated slotmeans will effect a camming displacement of said bulldozer blade to aposition of latching engagement with a leading edge of said bucketmeans.
 9. A combination bulldozer blade and bucket unit as described inclaim 8 further characterized in that said bulldozer blade includesabutment stop means detailed in location thereon for abutting contactwith an upper surface portion of said bucket in response to movement ofsaid bulldozer blade to said second bulldozer operating positions andwherein said camming operation of said pivot pin means and saidelongated slot means is effective in response to abutting contactbetween said bulldozer blade abutment stop means and said bucket.
 10. Acombination bulldozer blade and bucket unit as described in claim 9further characterized in that said elongated slot and pivot pin meansincludes spring biasing means for maintaining said pivot pin means in afirst position with said elongated slot during a first portion ofmovement of said bulldozer blade from said first bucket forming positionto a predetermined location relative to the leading edge of said bucketmeans and wherein said spring biasing means is yieldable in response tosaid bulldozer blade reaching said predetermined location for allowing ayielding movement of said pivot pin means relative to said elongatedslot means to effect said camming displacement of said bucket means tosaid latched position.
 11. A combination bulldozer blade and bucket unitcomprising, in combination: a. means on said unit defining a bucketmeans having a pair of horizontally spaced sidewalls and a bottom wallhaving a leading edge; b. a bulldozer blade having a bottom edge; c.means supporting said bulldozer blade on said unit for movement from afirst bucket forming position displaced rearwardly of said leading edgeto a second bulldozer operating position with said blade bottom edgebeing located in front of and below said bottom wall leading edge; d.control means operatively associated with said unit for effectingmovement of said bulldozer blade between said two positions, saidcontrol means including first linkage means pivotally connected to andoperable for supporting an upper portion of said blade, second linkagemeans connected to an intermediate portion of said blade, actuatingmeans operatively connected to said second linkaGe means for effectingmovement of said blade from said first position to said second position,and wherein said second linkage means is operatively connected to saidblade means for effecting a bodily translating movement of said bladefrom said first position to said second position, with said translatingmovement being in a first direction along a predetermined path andwherein said first and second linkage means and said actuating means areoperatively associated with each other and with said blade for effectingmovement of said blade in a second direction along a path angularlydisposed relative to said first direction in response to said bladereaching a predetermined location relative to the leading edge of saidbucket means; and e. said actuating means including a pivotally movablecrank arm means and said second linkage means including link meanshaving one end pivotally connected to an extended end of said crank armmeans and with a second end pivotally connected to said bulldozer blademeans, and yieldable latching means operatively associated with saidlink means for maintaining said link means in angularly set positionrelative to said bulldozer blade during movement of said bulldozer bladefrom said first bucket forming position to a predetermined positionlocated in front of the leading edge of said bucket means, saidyieldable latch means being operable for permitting pivotal movement ofsaid link means relative to said blade means in response to saidbulldozer blade reaching said predetermined position.
 12. A bulldozerblade and bucket unit as described in claim 11 further characterized inthat said yieldable latch means includes a pair of link elementspivotally connected to each other and with one of said link elementsbeing pivotally connected to said bulldozer blade means and said otherlink elements being pivotally connected to said second link means andwherein said link elements include limit stop means for controlling thepivotal movement of said link elements in a limit stop position in onedirection and permitting the pivotal movement of said link elements inan opposite direction and wherein spring biasing means is operativelyassociated with said link elements for biasing said link elements tosaid limit stop position.
 13. A bulldozer blade and bucket unit asdescribed in claim 12 further characterized in that said actuating crankarm means includes means for effecting movement of said link elements insaid opposite direction away from said limit stop position in responseto said bulldozer blade reaching said predetermined location forward ofsaid leading edge of said bucket means.
 14. Apparatus as in claim 8wherein said means for effecting movement of said bulldozer bladeincludes a hydraulic control cylinder means.
 15. Apparatus as in claim11 further including means for effecting a latching engagement betweenthe leading edge of said bucket means and a lower portion of saidbulldozer blade means when said last-mentioned means is in bulldozeroperating position.